Biology B3 - fast and slow twitch muscles Flashcards
What are the two different types of skeletal muscle fibres that are used to facilitate movement ?
Slow twitch fibres and Fast twitch fibres
what is slow twitch muscles fibres ?
slow twitch muscle fibres contract slowly and can work for a long time without getting tired.
what are slow twitch muscle fibres used for ?
They are good for endurance activities such as long distance running and pasture
where are slow twitch muscles found ?
They are found in muscles such as the calf muscle that needs to be working almost all of the time
what respiration are slow twitch muscles adapted to and why ?
They are adapted for aerobic respiration to avoid lactic acid build up as this would prevent long term contraction
why do slow twitch muscles have lots of mitochondria?
Lots of mitochondria and blood vessels to supply the muscles with oxygen and glucose for aerobic respiration
where are the mitochondria found in slow twitch muscles ?
The mitochondria are found near the edge of muscle fibres to provide a short diffusion pathway
why are slow twitch muscles typically red ?
Typically red in colour due to the dense supply of myoglobin , a bright red protein molecule that stores oxygen
what are fast twitch muscle fibres ?
They contract quickly but get tired quickly
what are fast twitch muscle fibres used for ?
They are good for short bursts of speed and power e.g. sprinting and strength
Where are fast twitch fibres found ?
They are common in muscles that need to do short bursts of intense exercise such as the biceps
what are the adaptations of fast twitch muscles ?
- Typically light in colour due to less mitochondria and fewer blood vessels
- Thicker and more numerous myosin filaments
- High glycogen concentration
- High concentration of enzymes involved in anaerobic respiration
- Store of phosphocreatine , a molecule that can rapidly generate ATP from ADP in anaerobic conditions and so provide energy for muscle contraction
a young athlete is very good at long distance running but is not good at sprinting. Discuss how this difference relates to the types of muscle fibre in their legs .
Young athletes muscle mainly composed of slow twitch fibres. Slow twitch fibres contain more myoglobin which stores oxygen. More mitochondria so more ATP made. More capillaries to deliver oxygen. Therefore, more aerobic respiration takes place. so less lactic acid is made . so less muscle fatigue so the athlete can run for longer.
Fast twitch muscle fibres contain less myoglobin which stores oxygen, Less mitochondria so less ATP made. Less capillaries to deliver oxygen . Therefore more anaerobic respiration takes place so more lactic acid is made. so more muscle fatigue, this means cannot run for longer.
